The present invention relates to a vehicle seat having a sitting surface and a backrest, and more particularly, to a seat with a backrest upholstery and a forward upholstery archingly arranged in the region of the lumbar vertebrae of the seat user for the purpose of relieving the intervertebral discs.
The forward upholstery arching in the backrest upholstery of the backrest is to ensure physiological back support (lumbar lordosis), in order largely to prevent the intervertebral disc of the seat user from being subjected to one-sided loads which lead to back complaints and, as a late consequence, often to damage to the intervertebral disc. In view of the widely varying body heights of seat users, such a forward upholstery arching can usually be configured in the most efficient possible way only for seat users of average body height, whereas other seat users of a body height differing from this have to tolerate a greater or lesser impairment of seat comfort.
In order to remedy this deficiency, the known backrest for a motor-vehicle seat shown in German Utility Model 7,434,028 uses a backrest plate covered by the backrest upholstery and installed in the backrest, and a self-locking lordosis support guided on the backrest plate so as to be vertically displaceable and arranged between the backrest upholstery and the backrest plate. The lordosis support is a shaped plastic hollow body which can be adjusted vertically by hand, specifically by gripping with both hands, until the seat user feels to be in the most comfortable possible sitting position and therefore believes that the lordosis support has the best possible setting.
The known backrest described in EP 0,153,390 B1 has an upright supporting frame and a flexible back support fastened to the supporting frame and curved outwards in relation thereto. To obtain a transverse region of rigidity for supporting the back in the upper pelvic area of the seat user, a regulating member extending transversely relative to the back support is arranged between the supporting frame and the back support. The regulating member can, by adjusting apparatus, be displaced vertically in the longitudinal direction of the curve of the back support and be set up, in order thereby to achieve a matching of the contour of the back support to the body height of the seat user and to his form of lordosis.
In both known backrests, the correct matching of the backrest contour to the height of the seat user has to be carried out by the seat user himself. Since there is no marking and measure of any kind for setting the forward upholstery arching so that it is as efficient as possible from an anthropometric point of view, he or she can adapt this only by feel and find the most agreeable forward upholstery arching only after a lengthy use of the seat. Moreover, such adjustment measures involve a high technical outlay and make the seat more expensive, often without affording the expected benefit, since many seat users avoid an individual adaptation of the back support for the sake of convenience. It can also happen that a user having a low lordosis vertex travels with a lordosis arch set very high. This eventually leads to an increased extent to the bad posture, mentioned above, which it is precisely the aim to avoid.
An object of the present invention is to provide a vehicle seat which offers a largely optimized back support for seat users of widely varying body height, specifically without the need for individual adjustment, and which, furthermore, is also inexpensive to produce.
The object has been achieved according to the present invention by configuring the forward upholstery arching such that its contour vertex is located approximately 250 to 275 mm above the sitting surface, the forward upholstery arching is sufficiently flexible in the region of the contour vertex that it easily matches the shape of the back of the seat user, and a relatively rigid pelvic support is formed in the forward upholstery arching approximately 150 to 175 mm above the sitting surface.
The advantage of the vehicle seat according to the present invention is that the backrest supports the spinal column of all seat users from the entire range of statistics on body measurements in the region of the lumbar vertebrae in a sufficiently effective way, without the need for them to carry out any manipulations on the back rest. As regards persons whose body height and therefore back length is in the upper range of statistics on body measurements, the pelvic support according to the present invention supports the upper half of the pelvis in the range between 150 and 175 mm above the sitting surface. In this group of people, the vertex of the forward upholstery arching, located approximately 250 to 275 mm above the sitting surface, is located in the lordosis curvature of the spinal column. The upholstery flexible according to the invention and located in this region fills the lordosis curvature of the seat user, without forcing his or her back into the predetermined upholstery curvature. As regards persons whose body height comes into the lower range of statistics on body measurements, the pelvic support supports both the upper edge of the pelvis and part of the lordosis curvature of the spinal column.. As a result of its flexibility, the vertex of the forward upholstery arching matches the shape of the back of the seat user. Altogether, the vehicle seat according to the present invention guarantees the best possible physiological back support for a large proportion of seat users and an at least sufficiently good back support for the rest.
According to a presently preferred embodiment of the present invention, an especially advantageous version of the relatively rigid pelvic support is achieved in that the backrest upholstery is undersprung over its entire upholstery region and the pelvic support is obtained by means of an underspringing which is clearly less resilient than in the remaining region of the backrest upholstery.